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VAMSI DANDA

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Electronics hobbyists enjoy playing with the projects.some people start a garage at home. For making any new invention you don't need any big laboratory. you can make your home a LAB.to work you just need a "multimeter". I have been working on some projects.At the beginning stage i made so many disasters in my room.I blasted so many components(one day i burnt my bed).what ever we do we enjoy that.So i just wanted to share some of my work with you.

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Thursday, 5 July 2012

This project is a microcontroller based line follower robot by using ATmega8 development board from "ROBOGENISIS". This development board consists of an on board USB programmer, motor driver and some other peripherals like LEDs, buzzers. This board is best for beginners.This can be programed using WinAVR,programers notepad.

ATmega8 microcontroller consist 3 ports:

PORTB an 8 bit I/O port

PORTC a 7 bit I/O port .But pin PORTC.6 is also RESET pin for the MCU so it cannot be used for input but remaining 6 pins can be used as inputs.

PORTD an 8 bit I/O port

In this board the ATmega8 works at 12 MHz crystal.

An on board L293D is used for driving motors. Separate power supply is provided motor driver and logic supply for MCU. Motor driver control pins are internally connected to the higher nibble (D7, D6, D5, and D4) pins of PORTD.

void main()
{
P1=0xff;//input for sensors make sure that all sensors are active high ( high for Wight)
//sensors are connected to lower two pins
//in 8051 to make a port input you need to write one's to the respected pins
unsigned char sensor;
//assume that motor control pins are connected to either upper or lower 4 bits of PORT2
while(1)
{
sensor=P1&0x03;
if(sensor==0x03)// both are on white
P2=0xaa;//forward
else if(sensor==0x01)//left sensor on black line
P2 =0x66;//left turn
else if(sensor==0x02)//right sensor on black line
P2 =0x99;//right turn
else
P2 =0x00;//robot stop

Wednesday, 4 July 2012

The most cheapest way of controlling the devises through wireless is IR remote.Every one in the world will have a TV remote which works based on RC5 protocol or some equivalent protocol.I searched over the internet for a perfect TV remote signal decoder compatible with all sensor like TSOP and other cheep TV sensor.I all ways thought of making such TV remote signal decoder.

But recently i found a TV signal decoder in Hyderabad.compatible with all most all TV remotes except for DVD,AC remotes.Actually it is a handmade one.I found it in a hobby shop.I bought for 295 Rs. i made some modifications regarding the power supply for direct 5V Vcc to the decoder module.
This one outputs a 5 bit address,6 bit data,a toggle bit and a valued data bit.
One important thing is the output form the decoder module will produce active low logic
if we press "2" on the remote the 6 bit data will be"111101"
if we press "4" on the remote the 6 bit data will be"111011"
if we press "0" on the remote the 6 bit data will be"111111"

I made a robot using that module.

I used a ATmega8 development board with ob board programmer for driving the motors as per the logic.
I removed the address pins on the decoder module and i connected the 6 bit address to the PORTC of ATmega8 and an L293D is used for driving motors which is internally connected to PORTD higher nibble on the development board.

Tuesday, 3 July 2012

Every beginner of microcontrollers all ways think of buying a prototyping board for practicing.Why don't you make your own board for working on your projects.I made a simple 8051 development board for prototyping my projects.You can make one by just spending less then 100 rupees.

For that you need very little equipment.

pin heads

40 pin IC base(i didn't get a 40 pin so i used a 42 pin)

a 7805 voltage regulator

crystal (11.0592Mhz or 12.0Mhz as per your requirement)

10kohm resistor

10kohm resistor 9 pin array

10uF electrolytic capacitor

33pF disc capacitors

some connecting wires

a special PCB that consists of all row holes will be connected

PROCEDURE

first take a PCB with all its row holes connected as shown in the figure

Cut the PCB as per the need of your size of board.First of all take a look at the pin diagram of AT89S52 microcontroller. The EA/VPP(pin 31) must be connected to VCC. The PORT0 must be pulled up through external pullups.So use the 9 pin 10K resistor array for pull up such that common pin to VCC and remaining 8 pins to PORT0 pins.

The power on reset circuit for 8051 will be as shown in the figure

Connection of external ceramic crystal to the AT89S51

arrange all the components as shown in the figure below. step by step

cut the PCB like this

place the 40 pin IC base(i used 42 pin as 40 pin is out of stock)

take some pin heads

place them as per the port pins

and place the remaining required components like crystal,reset circuit,7805 voltage regulator for supply

your home made prototyping board for AT89S51.
for programing the MCU you need a separate ISP programmer.
so many of them are available in the market.
if you use P89V51RD2 microcontroller you just need a max232 IC and a serial cable to program it